The parents of the British girl who went missing in Portugal are now under suspicion, but much about the case remains a baffling mystery. A look at the chief unanswered questions

The parents of missing toddler Madeleine McCann, Kate, background, and Gerry, carry their two-year-old twin children Sean and Amelie as they return to England four months after going on vacation on September 9, 2007. They deny any role in her disappearance.

On May 3, nine days before her fourth birthday, Madeleine McCann, a British girl on vacation with her parents in Portugal, disappeared. She hasn't been found in more than four months despite one of the most intensive and far-flung missing-person searches in history. This past spring and summer, Europe and much of the rest of the globe became fixated on the disappearance, which carries both the international breadth of the Diana tragedy and the hypersentimental, at times prurient fascination that Americans brought to the unsolved case of another little blond girl, JonBenét Ramsey.